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authorMatthew Wilcox <mawilcox@microsoft.com>2018-08-21 21:56:30 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2018-08-22 10:52:47 -0700
commitc430d1e848ff1240d126e79780f3c26208b8aed9 (patch)
treeaa2c5cd32056e24e075310d950f4385203c7cc87 /fs
parentee8ef0a4b167c1f2605bc9b5701c603224673d53 (diff)
userfaultfd: use fault_wqh lock
The userfaultfd code currently uses the unlocked waitqueue helpers for managing fault_wqh, but instead of holding the waitqueue lock for this waitqueue around these calls, it the waitqueue lock of fault_pending_wq, which is a different waitqueue instance. Given that the waitqueue is not exposed to the rest of the kernel this actually works ok at the moment, but prevents the userfaultfd locking rules from being enforced using lockdep. Switch to the internally locked waitqueue helpers instead. This means that the lock inside fault_wqh now nests inside the fault_pending_wqh lock, but that's not a problem since it was entirely unused before. [hch@lst.de: slight changelog updates] [rppt@linux.vnet.ibm.com: spotted changelog spellos] Link: http://lkml.kernel.org/r/20171214152344.6880-3-hch@lst.de Signed-off-by: Matthew Wilcox <mawilcox@microsoft.com> Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Mike Rapoport <rppt@linux.vnet.ibm.com> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Ingo Molnar <mingo@kernel.org> Cc: Jason Baron <jbaron@akamai.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Davidlohr Bueso <dave@stgolabs.net> Cc: Matthew Wilcox <willy@infradead.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'fs')
-rw-r--r--fs/userfaultfd.c6
1 files changed, 3 insertions, 3 deletions
diff --git a/fs/userfaultfd.c b/fs/userfaultfd.c
index 15c265d450bf..f649023b19b5 100644
--- a/fs/userfaultfd.c
+++ b/fs/userfaultfd.c
@@ -910,7 +910,7 @@ wakeup:
*/
spin_lock(&ctx->fault_pending_wqh.lock);
__wake_up_locked_key(&ctx->fault_pending_wqh, TASK_NORMAL, &range);
- __wake_up_locked_key(&ctx->fault_wqh, TASK_NORMAL, &range);
+ __wake_up(&ctx->fault_wqh, TASK_NORMAL, 1, &range);
spin_unlock(&ctx->fault_pending_wqh.lock);
/* Flush pending events that may still wait on event_wqh */
@@ -1066,7 +1066,7 @@ static ssize_t userfaultfd_ctx_read(struct userfaultfd_ctx *ctx, int no_wait,
* anyway.
*/
list_del(&uwq->wq.entry);
- __add_wait_queue(&ctx->fault_wqh, &uwq->wq);
+ add_wait_queue(&ctx->fault_wqh, &uwq->wq);
write_seqcount_end(&ctx->refile_seq);
@@ -1215,7 +1215,7 @@ static void __wake_userfault(struct userfaultfd_ctx *ctx,
__wake_up_locked_key(&ctx->fault_pending_wqh, TASK_NORMAL,
range);
if (waitqueue_active(&ctx->fault_wqh))
- __wake_up_locked_key(&ctx->fault_wqh, TASK_NORMAL, range);
+ __wake_up(&ctx->fault_wqh, TASK_NORMAL, 1, range);
spin_unlock(&ctx->fault_pending_wqh.lock);
}